EP3204782B1 - Method for determining characteristics of a partial discharge event - Google Patents

Description

The invention relates to a method for determining characteristics of a partial discharge process in a high voltage electrical component, in which a partial discharge is detected and measured, wherein at the high voltage component, a total voltage is applied as a superposition of a DC operating voltage and additionally of a time varying measuring voltage, and in that a charge difference caused by a partial discharge is detected several times relative to the total voltage and at the same time a phase reference of this partial discharge to the measuring voltage which changes over time in order subsequently to carry out an error detection on the basis of the characteristic properties of the phase reference of the multiply measured partial discharges.

Electrical high-voltage components that are part of a high-voltage system must have a sufficiently large and reliable insulation during operation in the high-voltage system to avoid electrical breakdown and damage caused by the high-voltage electrical components and the high-voltage system.

Often occur due to highly inhomogeneous field gradients spatially limited violations of a material-dependent breakdown field strength, so there are partial discharges in which insulation between the electrical high voltage component and a usually grounded potential surface is only partially bridged, so that only a partial discharge of the electrical high voltage component takes place and no more complete electrical breakdown occurs.

Such a partial discharge can have various causes. An external partial discharge arises between a surface of the high-voltage component in a surrounding air space, wherein audible and visible corona discharges preferably occur at sharp-edged areas of the high-voltage component. Within insulating media, internal partial discharges may occur in which discharges, but not complete breakdowns in the insulating medium, are favored by inhomogeneities of the insulating medium.

Both external partial discharges such as corona discharges and internal partial discharges within an insulating medium permanently lead to an impairment of the high voltage electrical component and possibly to damage and failure of the high voltage electrical component.

In order to damage the high voltage electrical components and thereby favored susceptibility of the high voltage component to electrical breakdown, which the electrical It is known from practice that partial discharges in the high-voltage electrical component are detected and metrologically detected in order to estimate and reduce the risk of a rapid impairment or destruction of the electrical high-voltage component in question severely or completely destroy high voltage component or destroy completely ,

For example in DE 28 56 354 or in DE 23 56 216 describes methods by which the partial discharges can be detected and evaluated, which are caused in a high voltage electrical component by a predetermined test voltage. It will be in DE 28 56 354 already indicated that the generation and a suitable coupling for the subsequent measurements of a test voltage can cause considerable difficulties. The measurement and evaluation of the individual partial discharges is also associated with problems, as for example in CN 102508031 A is described.

In an evaluation method known from practice, an alternating voltage can be applied to the high-voltage components to be tested, and the partial discharges detected or generated thereby can be detected. After a reference of the measured partial discharge has been made to a phase angle of the alternating voltage used for the measurement, conclusions can be drawn on the basis of the often characteristic distribution of individual partial discharges relative to the phase position of the impressed for the measurement of AC voltage Type of partial discharge and thus to be drawn on the possible effects of a fault that is present in the high-voltage component and could possibly soon lead to overuse and failure of the electrical high-voltage component during operation.

Investigations have shown that different sources of error, which are responsible for the occurrence of partial discharges during operation, each have characteristic and distinguishable dependencies on the AC voltage with which the partial discharges are detected during operation or at an increased test voltage. Based on the phase relationship to the exciting AC voltage that can be produced for each measured partial discharges, after a sufficiently large number of individual measurements of partial discharges, a correlation between the partial discharges and the partial discharges generating AC voltage can be produced and close to the cause of the individual partial discharges ,

In practice, therefore, various measuring methods have been developed, with the help of which, based on a number of partial discharges, which were enforced with an applied to the high voltage component AC voltage and detected by a measuring device, determine the type of partial discharge and thereby draw conclusions about the cause of the error and a Failure to close the high voltage component during further operation.

The measuring methods known from practice are based on a temporal assignment of individual partial discharges to an applied alternating voltage. On the other hand, if the electrical high-voltage component is operated with a DC voltage, partial discharges that occur can not be set in relation to a phase position of an excitation, so that the evaluation methods known from practice can not be used. If a partial discharge is excited by a DC voltage, therefore, no conclusions can be drawn on the type of fault and ultimately on the risk of failure of the relevant high-voltage component.

If the high-voltage component to be checked were disconnected from the DC voltage source and subjected to an AC voltage in order to be able to carry out the measurement and evaluation of the partial discharges using the measuring method known from practice, the effects of the DC voltage applied during operation of the high-voltage component would not occur during the measuring process and therefore can not be considered. Although the AC voltage applied separately instead of the DC operating voltage allows the detection of partial discharges, but does not allow reliable inference to occur during operation of the high voltage component with DC voltage partial discharges and the cause of the fault, or the risk of failure of the high voltage component when operating with DC voltage.

Out JP 2012 088080 or JP 2002 323533 It is in each case known to additionally connect a high-voltage component connected to a DC voltage source to an external AC voltage source and to superimpose the DC voltage generated during normal operation with an additional AC voltage in order to be able to measure and evaluate the partial discharges occurring during a test procedure. However, for this purpose, an individual adaptation of the AC voltage source and a suitable for carrying out the test process connection with the high-voltage component is required, which is associated with a considerable effort and usually with an at least temporary interruption of normal operation.

It is considered to be an object of the present invention to provide a method for determining characteristics of a partial discharge process in a high-voltage electrical component in such a way that during operation, high-voltage components subjected to a DC operating voltage can be measured and checked by the method.

This object is achieved according to the method claim 1, characterized in that the measuring voltage is generated from a residual ripple of the operating voltage generated from an AC voltage by either an already existing and a sufficiently large amplitude utilizing residual ripple or a ripple of the DC operating voltage is amplified to a Amplified ripple amplitude of at least 3%, preferably more than 10% and most preferably of more than 20% of the DC operating voltage. The high voltage required for the operation of the high-voltage electrical component is almost invariably generated in practice from an alternating voltage, which is converted by means of a rectifier device into a constant as possible DC operating voltage. In this case, even with complex rectifier devices, a completely constant DC operating voltage is often not achieved, but the voltage fluctuations of the AC voltage are largely, but not completely reduced. The residual ripple is a characteristic of the periodic voltage fluctuations remaining after rectification of the AC voltage, which can be reduced to less than 1% to 2% of an output amplitude of the AC voltage in efficient rectifier devices.

This residual ripple usually has regular periodic fluctuations whose phase and frequency are predetermined by the alternating voltage used for generating the operating DC voltage. It has been shown that even with a slight amplification of this residual ripple, a regular periodic AC voltage component can be generated, which is superimposed on the DC operating voltage. The appropriately amplified residual ripple allows for occurring partial discharges simultaneously determining a phase reference of the generated partial discharges with the increased ripple, which allows the error assignment of the partial discharges.

The as efficient as possible rectification of the AC voltage during regular operation of the high voltage component can thereby be selectively influenced in order to maintain a periodically fluctuating AC voltage component, which is superimposed on the DC component generated by the incomplete rectification. The modification of the rectification can be carried out, for example, by a targeted erroneous control of the semiconductor elements used for the rectification or optionally by an adjustment of the ignition angles of the semiconductor elements.

According to an advantageous embodiment of the inventive idea it is provided that the phase reference is detected in a separate measuring branch relative to the measuring voltage and separated from a measuring branch for the measurement of the partial discharge. The partial discharge or a charge difference caused thereby can be detected in a measuring branch relative to the operating DC voltage or to the total voltage generated by superimposition. A measurement of the phase reference relative to the measurement voltage and a measurement of the partial discharge relative to the DC operating voltage or the total voltage is taken in the sense of the present invention as a measurement, which are carried out at areas of the high voltage components or the voltage source associated with these high voltage components, in which predominantly or exclusively the measuring voltage, or the DC operating voltage or the resulting total voltage is applied. A measurement in separate measuring branches can be a spatially-spaced measurement of the Include phase reference and partial discharge. However, it is not considered to be a measurement in separate measuring branches when the measurements are made with series-connected measuring equipment or even with the same measuring equipment.

The measurement of a partial discharge can be carried out, for example, by means of a first coupling capacitor, which is arranged between the high-voltage component charged with the operating DC voltage or with the total voltage and an earth conductor. The measurement of the phase reference of a partial discharge measurement carried out in this way can be carried out on an AC voltage source which generates the DC operating voltage applied to the high-voltage component with the aid of a rectifier device. It merely has to be ensured that a phase position, determined during a partial discharge measurement, of the time-varying measuring voltage to the AC voltage source has a time-known dependence, which is decisive for the measured partial discharge.

By also existing in terms of spatial separation of the measurement of the partial discharge on the one hand and the measurement of the phase reference of this partial discharge to the causative and temporally changing measurement voltage on the other hand, a characteristic of a given error type dependence of the partial discharges can be determined and evaluated by the respective phase.

It is advantageously provided that the partial discharge is determined with the aid of a first coupling capacitor, that the phase reference is determined by means of a second coupling capacitor, wherein the capacitance C _{k2 of} the second coupling capacitor is substantially greater than the capacitance C _{k1 of} the first coupling capacitor. The charge differences occurring at the first coupling capacitor and at the second coupling capacitor and thus compensating currents can be determined and evaluated cost-effectively and extremely reliably precisely with the aid of four-pole or two-port circuits.

It is also conceivable and advantageous for certain applications that the determination of the phase reference is triggered by means of a light signal of a light-emitting diode fed by the measuring voltage. Commercially available electronic measuring components are known with the aid of which an occurring charge difference can be set in a temporal relation to an externally generated light signal or more generally in a relation to a triggered time information. A suitable light signal can be generated with commercially available and inexpensive components, with a high sensitivity of the light signal with respect to the time varying measuring voltage. With such a measuring process step can be reliably and with high accuracy detected a change over time of the measuring voltage and used for the determination of the phase reference of a simultaneous partial discharge and used.

A particularly advantageous embodiment of the inventive concept is provided that as Measuring voltage is used an AC voltage whose peak value has less than 50% of the DC operating voltage, preferably less than 30% and more preferably less than 15% of the DC operating voltage. The AC voltage can be generated for example by a transformer which is integrated at a suitable point in the power supply of the high-voltage component.

It has been found that in many cases only an alternating voltage with a small amplitude compared to the operating DC voltage is required in order to generate and evaluate the partial discharges required for fault detection. By superimposing the DC operating voltage with an AC voltage, which may for example have a frequency of 50 Hz, but also a lower or significantly higher frequency, a large number of partial discharges can be enforced and evaluated within a short measurement period. The measurement of the phase reference can be made in a simple manner to the AC voltage or derived from the known specifications in the generation of the AC voltage and correlated with the measured partial discharges.

According to one embodiment of the inventive concept it is provided that the high-voltage component is repeatedly applied with a pulse-shaped surge voltage.

It is also conceivable, in particular, for a high-voltage component designed as a high-voltage cable, that the high voltage component is applied to a traveling wave.

According to a further embodiment of the inventive concept it is provided that in each case only the positive or the negative DC operating voltage component is subjected to a rectified AC voltage.

Within the scope of an evaluation of the measurement results of the partial discharge measurement system according to the invention, it is provided that an analysis of the measurement results with the aid of statistical evaluation methods is used to detect complex or superimposed partial discharges.

Preferably, a targeted measurement of partial discharges of the positive or negative polarity via the coupling out with the aid of low-voltage side coupling capacitors via switching devices.

• Fig. 1 eine schematische Darstellung einer Messeinrichtung für eine Hochspannungskomponente, wobei über einen ersten Koppelkondensator und einen ersten Vierpol ein Phasenbezug zu einer Wechselspannung ermittelt und über einen zweiten Koppelkondensator und einen zweiten Vierpol eine Teilentladung in einer Hochspannungskomponente ermittelt wird, an der eine Betriebsgleichspannung und eine sich mit der Zeit verändernde Messspannung anliegt,
• Fig. 2 eine schematische Darstellung einer abweichend ausgestalteten Messeinrichtung, bei der über einen Transformator eine Wechselspannung als Messspannung eingekoppelt wird und die Ermittlung des Phasenbezugs relativ zu der Wechselspannung über einen ersten Koppelkondensator und einen ersten Vierpol ermittelt wird,
• Fig. 3 eine schematische Darstellung einer abweichend ausgestalteten Messeinrichtung, bei der eine Leuchtdiode in Abhängigkeit von der zeitlichen Veränderung des Messspannungsanteils in einem gesonderten Messzweig aufleuchten und eine Ermittlung eines Phasenbezugs auslösen,
• Fig. 4 eine schematische Darstellung einer Anzahl von gemessenen Teilentladungen in Abhängigkeit von der jeweils zugeordneten Phasenbeziehung, wobei die Teilentladungen ausschließlich durch eine Gleichspannung erzeugt sind,
• Fig. 5 eine schematische Darstellung einer Anzahl von gemessenen Teilentladungen in Abhängigkeit von der jeweils zugeordneten Phasenbeziehung, wobei die Teilentladungen durch eine Messspannung mit einem Wechselspannungsanteil von 5 kV ausgelöst sind, die einer Gleichspannung von 50 kV überlagert ist, und wobei die Teilentladungen durch Lunker in einem Isolierungsmaterial der Hochspannungskomponente verursacht werden,
• Fig. 6 eine schematische Darstellung einer Anzahl von gemessenen Teilentladungen in Abhängigkeit von der jeweils zugeordneten Phasenbeziehung, wobei die Teilentladungen durch eine verstärkte Restwelligkeit der aus einer Wechselspannung erzeugten Gleichspannung ausgelöst sind, und wobei die Teilentladungen durch eine äußere Korona-Entladung verursacht werden,
• Fig. 7 eine schematische Darstellung einer Überlagerung einer Wechselspannung mit Hilfe eines in Reihe geschalteten und über Koppelkondensatoren eingebundenen Transformators mit einem geerdeten Mittenabgriff,
• Fig. 8 eine schematische Darstellung einer abweichend ausgestalteten Überlagerung einer Wechselspannung, die durch zwei separate Transformatoren über hochspannungsseitig angeordnete Koppelkondensatoren der Gleichspannung überlagert wird, und über niederspannungsseitig angeordnete Koppelkondensatoren eine Teilentladungsmessung erfolgt,
• Fig. 9 eine schematische Darstellung einer wiederum abweichend ausgestalteten Überlagerung einer Wechselspannung, die über einen Transformator mit geerdetem Mittenabgriff eingekoppelt wird, und wobei eine Teilentladungsmessung über hochspannungsseitige und niederspannungsseitige Koppelkondensatoren erfolgt,
• Fig. 10 eine schematische Darstellung einer Messeinrichtung für eine Hochspannungsanlage mit einer Betriebsgleichspannungsquelle, einer alternativ zuschaltbaren Prüfspannungsquelle, einer zu prüfenden Hochspannungskomponente und einer wahlweise zuschaltbaren oder trennbaren Verbraucherlast,
• Fig. 11 eine schematische Darstellung einer abweichend ausgestalteten Messeinrichtung, bei der ausgehend von einer Wechselspannung eine modifizierte Gleichrichtung erfolgt, so dass einem Gleichspannungsanteil ein Wechselspannungsanteil überlagert wird,

• Fig. 12 eine schematische Darstellung einer wiederum abweichend ausgestalteten Messeinrichtung, wobei eine Restwelligkeit einer Gleichspannungsquelle verstärkt und der Gleichspannung überlagert wird,
• Fig. 13 eine schematische Darstellung einer wiederum abweichend ausgestalteten Messeinrichtung, wobei ein Spannungsimpuls als Messspannung eingekoppelt wird,
• Fig. 14 und 15 eine schematische Darstellung von polaritätsabhängigen Messungen von Teilentladungen in oder an der Hochspannungskomponente.

Embodiments of the inventive concept will be explained in more detail, which are illustrated in the drawing. It shows:

• Fig. 1 a schematic representation of a measuring device for a high voltage component, wherein via a first coupling capacitor and a first quadrupole a phase reference to an alternating voltage determined and a second coupling capacitor and a second quadrupole a partial discharge in a high voltage component is determined, at which a DC operating voltage and with the Time-varying measuring voltage is applied,
• Fig. 2 a schematic representation of a deviating designed measuring device, in which via a transformer an AC voltage is coupled as a measuring voltage and the determination of the phase reference relative to the AC voltage across a first coupling capacitor and a first quadrupole is determined
• Fig. 3 a schematic representation of a deviating designed measuring device, in which a light emitting diode in dependence on the temporal change of the measuring voltage component in a separate measuring branch light up and trigger a determination of a phase reference,
• Fig. 4 a schematic representation of a number of measured partial discharges as a function of the respectively associated phase relationship, wherein the partial discharges are generated exclusively by a DC voltage,
• Fig. 5 a schematic representation of a number of measured partial discharges depending on the respective associated phase relationship, wherein the partial discharges are triggered by a measuring voltage with an AC component of 5 kV, which is superimposed on a DC voltage of 50 kV, and wherein the partial discharges by voids in an insulating material of the High voltage component caused
• Fig. 6 a schematic representation of a number of measured partial discharges in dependence on the respectively associated phase relationship, wherein the partial discharges by an increased residual ripple of a AC voltage generated are triggered, and wherein the partial discharges are caused by an external corona discharge,
• Fig. 7 a schematic representation of an overlaying of an alternating voltage by means of a series-connected and integrated via coupling capacitors transformer with a grounded center tap,
• Fig. 8 a schematic representation of a differently designed superimposition of an alternating voltage, which is superimposed by two separate transformers via high-voltage side arranged coupling capacitors of the DC voltage, and via low-voltage side arranged coupling capacitors, a partial discharge measurement,
• Fig. 9 a schematic representation of a turn differently designed superposition of an AC voltage, which is coupled via a transformer with grounded center tap, and wherein a partial discharge measurement via high-voltage side and low-voltage side coupling capacitors,
• Fig. 10 a schematic representation of a measuring device for a high voltage system with a DC operating voltage source, an alternatively switchable test voltage source, a high voltage component to be tested and an optionally switchable or separable load load,
• Fig. 11 a schematic representation of a differently configured measuring device in which, starting from an AC voltage, a modified rectification, so that a DC voltage component is superimposed on an AC component,

• Fig. 12 a schematic representation of a turn deviating designed measuring device, wherein a residual ripple of a DC voltage source is amplified and the DC voltage is superimposed,
• Fig. 13 a schematic representation of a again deviating designed measuring device, wherein a voltage pulse is coupled as a measuring voltage,
• FIGS. 14 and 15 a schematic representation of polarity-dependent measurements of partial discharges in or on the high voltage component.

Fig. 1 shows a schematic representation of a measuring device 1 for a high voltage component 2, which is shown by way of example as part of a high-voltage system not shown in detail. The high-voltage component 2 is supplied and operated via a DC voltage device 3 during operation of the high-voltage system with a DC operating voltage. The DC voltage device 3 is fed from an AC voltage device 4 whose AC voltage is rectified by a rectifier device 5 and converted into a DC voltage. After the rectifier device 5 is an amplifier device 6 with an integrated arranged electronic control with which the ripple of the rectifier device 5 is amplified and superimposed as an AC component of the DC voltage component generated with the rectifier device 5.

Via a first coupling capacitor 7 with a capacitance C _k1 and a first quadrupole 8, a phase reference to the alternating voltage is determined, which has a temporal correlation to the amplified residual ripple, which is superimposed as a time-varying measuring voltage of the operating DC voltage. Via a second coupling capacitor 9 with a capacitance C _k2 and a second _quadrupole 10, a partial discharge in the high-voltage _component 2 is determined. The measurement signals of the first quadrupole 8 and the second quadrupole 10 are fed to a partial discharge measurement system 11. The capacitance C _k2 is much larger than the capacitance C _k1 .

After measuring a sufficiently large number of partial discharges and the associated phase references, the determination of parameters of the partial discharge process can be carried out, which will be described in more detail below.

In Fig. 2 By way of example, a schematic representation of a differently configured measuring device 1 is shown. Instead of the amplifier device 6, with which a ripple amplified and the DC voltage is superimposed, an AC voltage or a voltage pulse is generated by a suitable transformer 12 and transformer and arranged on a high voltage side third coupling capacitor 13 of the DC voltage superimposed. The first quadrupole 8 is coupled via the first coupling capacitor 7 to the AC voltage generated by the transformer 12 and allows a determination of the phase reference via the AC voltage, which is superposed as a measuring voltage changing over time. The capacitance C _k3 is substantially larger than the capacitance C _k2 , which in turn is substantially larger than the capacitance C _k1 .

The phase position of the alternating voltage, which is coupled via the transformer 12, can also be transmitted by suitable means directly to the partial discharge measuring system and fed to a further evaluation.

Fig. 3 shows a schematic representation of a turn deviating configured measuring device 1, in which a freewheeling diode 14 and a light emitting diode 15 depending on the change in the measured voltage component in a separate measuring branch 16 light up. The light emission of the light-emitting diode 15 correlates with the temporal change of the amplified residual ripple, which is superimposed on the DC voltage as a periodically oscillating measuring voltage. By detecting and evaluating the optical signals of the light-emitting diode 15, the phase reference of the partial discharges measured at the same time can be determined.

In the 4 to 6 each measurement results of a large number of partial discharges are shown. The respectively measured charge quantities of the partial discharges are plotted in standardized charge units along the Y-axis. Along the X-axis is the phase reference over a complete oscillation of 360 ° is applied. Such representations are referred to in practice as a phase / frequency-related matrix or as a PRPD pattern.

In Fig. 4 schematically a number of measurement results of the partial discharge measurement system is shown, wherein the partial discharges were generated by a non-inventive method exclusively by a DC voltage. The individual partial discharges are distributed essentially uniformly over the period of oscillation of the exciting alternating voltage, so that no characteristic phase reference is recognizable.

In Fig. 5 schematically shows a number of measurement results of the partial discharge measurement system, the partial discharges were triggered by a measuring voltage with an AC voltage component of 5 kV, which was superimposed on a DC voltage of 50 kV. The partial discharges were caused by voids in an insulating material of the high voltage component used for the measurements. Clearly visible are two focal points of the frequency distribution of the partial discharges in dependence on the phase reference of the partial discharges at a phase angle of 50 ° and at a phase angle of 230 °. Based on such a characteristic frequency distribution can be on the nature of the cause of the error, here a voids in the insulation material closed.

In Fig. 6 schematically shows a number of measurement results of the partial discharge measuring system, wherein the Partial discharges were excited by an increased ripple of the DC voltage generated from an AC voltage. The partial discharges were caused by an external corona discharge. Here, too, a characteristic frequency pattern that deviates significantly from a uniform distribution is discernible, which differs from the one in Fig. 5 differs and also allows conclusions about the nature of the cause of the error.

In the Fig. 7 to 9 different embodiments of the coupling of an alternating voltage as shown over time changing measuring voltage and the decoupling of the partial discharge measurement are shown schematically. Such coupling of an alternating voltage is in addition to the use according to the invention of the residual ripple.

At the in Fig. 7 In the embodiment shown, the alternating voltage is generated with the aid of a series-connected transformer 18 connected via two coupling capacitors 17 with a grounded center tap 19 and superimposed on the DC voltage of the DC voltage device 3.

At the in Fig. 8 In the embodiment shown, the AC voltage is superimposed by two separate transformers 20 and 21 via high voltage side arranged coupling capacitors 22 of the DC voltage, and decoupled via low-voltage side arranged coupling capacitors 23, a partial discharge measurement.

At the in Fig. 9 In the embodiment shown, the AC voltage is coupled in separately from the output of the partial discharge measurement.

In the Fig. 10 to 13 different variants of the coupling or generation of the measuring voltage are shown, with which each of the high-voltage component 2 is applied. The high-voltage component 2 is shown merely by way of example as a transmission path and an electrically conductive connection to an electrical load or a load 24. The load 24 may be connected to or disconnected from the high voltage component 2 either during the performance of a measurement, depending on the characteristics of the load 24. These embodiments correspond to the measurement of partial discharges in a high voltage cable connecting a load 24 to a DC voltage device 3.

In Fig. 10 For example, the DC voltage device 3 used during a common use of the high-voltage cable can be disconnected and replaced by a test voltage source 25 which generates a DC voltage component and a superimposed AC voltage component. The DC voltage component of the test voltage source 25 corresponds approximately to the DC operating voltage that is generated by the DC voltage device 3 during operation. The AC voltage component has an amplitude of less than 50% of the DC operating voltage.

In Fig. 11 the measured voltage superimposed on the DC voltage, which corresponds to the test voltage source 25, generated by a modified rectification of the AC voltage from which the rectifier device 5, the DC operating voltage is generated.

In Fig. 12 the measuring voltage is generated and superimposed by an amplification of the residual ripple of the rectified operating DC voltage with the aid of the amplifier device 6.

In Fig. 13 schematically shows that the measuring voltage is generated for example with a Marx generator 26 as a voltage pulse on the high voltage cable and causes a traveling wave, which is used as a time-varying measuring voltage.

The FIGS. 14 and 15 each show a schematic representation of polarity-dependent measurements of partial discharges in the high-voltage component. The partial discharge measuring system 11 is in each case arranged parallel to a measuring voltage branch 26 with a polarity-dependent coupled alternating voltage.

Claims (10)

1. A method for determining characteristics of a partial discharge event in an electric high-voltage component (2), in which a partial discharge is detected and measured, wherein a total voltage as a superposition of an operating DC voltage and additionally a time-variant measuring voltage is applied to the high-voltage component (2), and wherein a charge difference caused by the partial discharge and a phase relation to the time-variant measuring voltage is detected multiple times simultaneously, in order to subsequently carry out an error identification by means of the characteristic properties of the phase relation of the partial discharges measured multiple times, characterized in that the measuring voltage is generated based upon a ripple of an operating DC voltage generated from of an AC voltage, in that a ripple of the operating DC voltage is amplified to obtain an amplitude of the amplified ripple of at least 5 %, preferably more than 10 %, and particularly preferably more than 20 % of the operating DC voltage, and that a dependency of the partial discharges on the respective phase position, which is characteristic to a specified error type, is determined and evaluated.
2. The method according to claim 1, characterized in that the phase relation is detected in a separate measuring branch relative to the measuring voltage, and separately from a measuring branch for the measuring of the partial discharge.
3. The method according to claim 2, characterized in that the partial discharge is determined using a first coupling capacitor (7), that the phase relation is determined using a second coupling capacitor (9), wherein the capacitance C_k2 of the second coupling capacitor (9) is significantly higher than the capacitance C_k1 of the first coupling capacitor (7).
4. The method according to claim 2, characterized in that the determination of the phase relation is triggered using a light signal of a light-emitting diode (14, 15) powered by the measuring voltage.
5. The method according to one of claims 1 to 4, characterized in that an AC voltage is used as the measuring voltage, the peak value of which amounts to less than 50 % of the operating DC voltage, preferably less than 30% and particularly preferably less than 15 % of the operating DC voltage.
6. The method according to one of claims 1 to 5, characterized in that a pulse-type surge voltage is repeatedly applied to the high-voltage component (2).
7. The method according to one of claims 1 to 6, characterized in that a travelling wave is applied to the high-voltage component (2).
8. The method according to one of claims 1 to 5, characterized in that in each case only the positive or the negative operating DC voltage component is applied with a rectified AC voltage.
9. The method according to one of claims 1 to 8, characterized in that via switching means, a targeted measuring of partial discharges of the positive or negative polarity occurs via the decoupling using low-voltage-side coupling capacitors.
10. The method according to one of claims 1 to 9, characterized in that an analysis of the measuring results using statistical evaluation methods is used to detect complex or superimposed partial discharges.

Images